WASHINGTON — Big banks now know: Virgin billionaire Sir Richard Branson has them in his crosshairs.

He told a full house at BAI Retail Delivery at the Washington convention center on Tuesday that even though his new bank, Virgin Money,only kicked into high gear a few months ago when he purchased the remains of failed United Kingdom bank Northern Rock, “we already originate one in three new mortgages in the UK.”

Branson paid 747 million pounds – roughly $1.2 billion – for Northern Rock, an institution taken under public ownership in 2008 after a run on its assets.

“Northern Rock went spectacularly wrong. We decided to try to save it,” said Branson, who started by changing the name – “the brand was damaged” – to Virgin Money.

Branson (ranked number 255 on the Forbes rich list, with $4.2 billion) made plain that he has built his companies and earned his fortune going after conglomerates that, he believes, need shaking up.

He has done it, with some success, in music, in air transportation, in telephony, and in a number of other businesses. He clearly believes that an historic opportunity exists to go after a sizable share of banking which, mainly, is controlled by a small handful of institutions in the United Kingdom. “But our rivals have been badly damaged,” said Branson.

“I look for areas where we can improve on how other companies do it,” said Branson who emphasized that it is important to deliver an experience that is fun for customers, but it also has to be an experience where every little detail is done right.

With Virgin Money branches, Branson said, his aim has been to remake them so they have the look and feel of a first class airport lounge.

“We want to give people a banking experience that is fun, pleasant. The first thing I did was take a sledgehammer and knocked down the iron bars that separate tellers from customers,” he said.

Is Virgin Money coming to the United States – keeping in mind that Branson already operates airlines here and his Virgin Mobile is a force in the discount cellular market? The usually voluble Sir Richard turned coy on that point, admitting “we have a team in the U.S. presently looking for opportunities for us. But we have no immediate plans. One day we will enter this market.”